Air

Our air Lidia Morawska Go to Brisbane’s Mount Coot-tha Lookout on a crisp, bright morning and look east: in glittering sunlight, you will clearly see the shores of Moreton Island. Now look south: towering on the horizon you see the unmistakable shape of Mount Warning. 1 A light wind gently flows around your head and it feels like there is nothing between your eyes and the island and the mountain. Nothing? Each square centimetre of air (the size of a cube of a sugar) contains almost 30 quintillion gas molecules (~3 x 10 19 )! Multiply this by the distance light travels between your eye and these geographical sites and the number of molecules making up the air will be beyond your comprehension. Now look up! You will (usually) see an immensely blue sky above you. Why is it blue and how far does it extend? It extends to the infinite reaches of the universe, and into its cold and silent darkness. It is the air — the atmosphere of the Earth — that makes it blue (by scattering more solar radiation of this wavelength). And it is because of the air that you and I are alive — without it, we would just be molecules of the cold cosmos. The atmosphere allows visible light from the Sun to pass through, so we can see. It keeps heat in (infrared radiation) to keep the Earth warm, and without it we would freeze to death instantly. It also filters out most of the ultraviolet radiation emitted by the Sun, which would harm us. The Earth’s atmosphere is like a magical blanket keeping us safe. 1 Mount Coot-tha Lookout, a short drive from Brisbane’s CBD, is at the top of Mount Coot-tha Reserve, an area containing over 1600 hectares of largely open eucalypt forest. Home to 370 wildlife species and 450 native plant species, Mount Coot-tha is a derivation of the Aboriginal word ‘kuta’, meaning honey. Brisbane sky 2022 65 Our air